w,h,c=input().split();f=[0,1][c=='W']
for i in range(int(h)):
	for j in range(int(w)):
		if not int(w)%2 and i%2:
			print(['B','W'][not f%2],end='')
		else:
			print(['B','W'][f%2],end='')
		f+=1
	print()